Download
1 / 37
380 likes | 594 Views
Water. Fresh Water. Two types of standing bodies of water: Lakes Wetlands Lakes are formed when a depression in the ground fills with water Water can come from rivers, springs, rain, melting snow, or surface runoff Lakes have 4 zones: littoral, limnetic, profundal , benthic. Lakes.
E N D
Fresh Water • Two types of standing bodies of water: • Lakes • Wetlands • Lakes are formed when a depression in the ground fills with water • Water can come from rivers, springs, rain, melting snow, or surface runoff • Lakes have 4 zones: littoral, limnetic, profundal, benthic
Lakes • Littoral is the shallow zone located at the top of a lake and exposed to sunlight; Life forms include crustaceans and amphibians • Limnetic zone is in the middle of the lake; life forms include plankton and predators
Lakes • Profundal is the deeper zone that received little sunlight; life forms include detritivores • Benthic is the layer of sediment at the bottom of a lake; life forms include insects and tiny crustaceans
Wetlands • Wetlands are land that is saturated with water • 2 types: marshes and swamps • Marshes form as sediment accumulates at the bottom of a lake and oxygen runs out which leads to grassy vegetation taking over • In contrast swamps have a woody vegetation
Wetlands • Wetlands are important for several reasons • Protect the land from flooding • Recycle nutrients into the soil • Purify water by removing pollutants • Provide shelter for animals • Home to unique carnivorous plants and rare reptiles and amphibians
Rivers • Rivers are an important source of fresh water, containing less than 1% dissolved salts • Rivers begin at headwaters, with sources including springs, lake, or runoff • As the water flows downhill it speeds up (greater gradient), picks up sediment (speed dependent) , and water • The bottom of the river wears away as the rocks move along • Rivers end at the mouth at another body of water
Rivers • Young rivers typically have a fast movement speed, can carry large rocks, have few tributaries or meanders • Mature rivers move slower, can carry smaller rocks, have many tributaries, and no meanders • Old rivers move slow, can only carry sand and mud, have fewer tributaries, and many meanders
Stages ofStream/River Development Rivers Young stream Steep Slope Mature stream Moderate Slope Old stream Gentle Slope http://www.dkimages.com/discover/previews/774/206778.JPG
Flooding • Flooding has both positive and negative consequences • Flooding deposits fertile soil in a delta and a flood plain • Deltas are alluvial deposits at the mouth of the river, deposited as the water slows down • Flood plains are flat land next to the river that becomes covered with water during a flood; when the river floods silt, sand, or gravel is left behind
Flooding • Floods can also cause serious damage (Hurricane Katrina) • Levees are barriers along riverbanks that prevent water from overflowing (natural or manmade) • Sandbags are bags dropped continually to repair breaches (water getting through) • Dams are huge walls that stand in the way of rising waters
Watershed • A watershed is an area of land from which water flows into a river, stream, lake or ocean • Vary in size, Mississippi River watershed covers 40% of the US • Pollution in a watershed can affect all organisms in the watershed • Non-point pollution from farms, urban runoff, and other sources • Point source pollution (factories) can pollute entire watersheds
Underground water • Underground water reserves are located around the world and are vital to life on Earth • Seeps into porous soil or rocks underground • Gravity moves water and replenished by water cycle • Provides drinking water to ½ world population and important for agriculture and industry
Underground water • Zone of aeration is the underground layer that contains empty spaces and spaces filled with water (relatively dry) • Water table is boundary between the zone of aeration and the zone of saturation; minimum depth to drill to receive reliable supply of water • Zone of saturation is the underground layer which all pores are filled with water (lowest) • Impermeable rock is underground layer that has no empty spaces
Ground water • Infiltration is the movement of water from the ground surface into the soil • Soil properties affect infiltration: porosity, permeability • Gravity • Capillary action is the movement of water in porous areas (can fight gravity)
Underground water • Aquifers is a body of saturated rock through which water can easily move, must have layers of permeable and impermeable rock • Unconfined aquifer’s upper boundary is the water table, less protected and easily polluted • Confined (artesian) aquifer are sandwiched between two impermeable layers, more protected and less likely to be polluted
Underground water • Underground water can surface in several ways • Artesian spring: water flows sideways and bursts through the surface • Artesian well (confined aquifer): drilling into aquifer causes water to come to surface (no pump) due to pressure • Geyser: water is heated underground and bursts through the surface • Man-made well: water is pumped above ground • Hot spring: spring whose water is heated underground by molten rock
Ocean Waves • Wind energy is transferred through friction and creates waves on the ocean’s surface • As waves come ashore the ground slows it down and causes it to topple over itself • Erodes structures including cliffs, notches, sea caves, sea arches, sea stacks
Ocean Waves • Parts: • Crest: top of the wave • Trough: lowest point between two crests • Wave period: time it takes for two consecutive crests to pass a fixed point • Wave height: distance between the trough and crest • Wavelength: distance from one crest to the next • Wave base: half the wavelength
Ocean Tides • Tides are caused by gravity from the pull of the sun and moon on Earth • Spring tides are the highest and lowest tides which occur during a full moon or new moon (sun and moon are aligned) • Neap tides are the smallest tides which occur during the first and last moon quarters (sun and moon are not aligned)
Ocean Currents • Ocean currents are caused by different temperatures and densities • Surface currents result from the effects of the wind • Deep currents are caused by temperature and density differences • The currents generally move by cold water travelling from the Poles to the equator; warm water travels from the equator to the Poles
Ocean Currents • The Coriolis Effect prevents water and air from travelling in a straight line • Deflected by the motion of the Earth’s rotation
Oceans • Water at the equator is typically warm and has a lower density • Water at the poles is typically cold and has a higher density
Sea Level Change • Many are concerned that global warming could cause the sea level to rise • Temperatures increase due to global warming • Glaciers melt • Sea level rises due to increase in ocean volume • Erosion and flooding
Currents and Weather • Changes in oceanic and atmospheric currents can have drastic effects on the weather • Normal conditions • Western Pacific is typically very warm and rainy because easterly trade winds bring warmth and push water toward the west; pressure is lower • Eastern Pacific is typically cooler air because winds blowing away warmth; pressure is higher
El Nino/ Southern Oscillation • The wind-driven movement of warm water in the Pacific shifts, causing extreme disruptions to weather systems around the globe • Western, tropical Pacific has higher air pressure, and eastern Pacific is lower • Trade winds are weakened and causes them to blow backwards (west to east) • Eastern Pacific is warmer and receives more rain, western Pacific is cooler and drier; eastern Pacific has less nutrient-rich water • Occurs every 3-7 years and lasts ~18 months
La Nina • Pressure and trade winds reverse dramatically • Dramatic upwelling occurs in eastern Pacific, resulting in very cold water • Western Pacific is wetter than normal • Eastern Pacific is drier than normal • Lasts 9-12 months
http://video.nationalgeographic.com/video/el-nino • https://www.youtube.com/watch?v=IvmeUStFvz8
